arm: ARMv4 assembly compatibility

There is currently a problem that U-Boot can not work on ARMv4
because assembly imlementations of memcpy() and some other functions
use "bx lr" instruction that is not available on ARMv4 ("mov pc, lr"
should be used instead).

A working preprocessor-based solution to this problem is found in
arch/arm/lib/relocate.S. Move it to the "ret" macro in
arch/arm/include/asm/assembler.h and change all "bx lr" code
to "ret lr" in functions that may run on ARMv4. Linux source code
deals with this problem in the same manner.

v1 -> v2:
Comment update. Pointed out by Andre Przywara.

Signed-off-by: Sergei Antonov <saproj@gmail.com>
CC: Samuel Holland <samuel@sholland.org>
CC: Ye Li <ye.li@nxp.com>
CC: Simon Glass <sjg@chromium.org>
CC: Andre Przywara <andre.przywara@arm.com>
CC: Marek Vasut <marex@denx.de>
CC: Sean Anderson <sean.anderson@seco.com>
CC: Tom Rini <trini@konsulko.com>

diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index b146918586015da8229ac85cd5662d83b927e6fd..8d42ef4823e9fdc2cc6a25cb79612d9b08a98eec 100644 (file)
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -58,16 +58,22 @@
 #endif
 
 /*
- * We only support cores that support at least Thumb-1 and thus we use
- * 'bx lr'
+ * Use 'bx lr' everywhere except ARMv4 (without 'T') where only 'mov pc, lr'
+ * works
  */
        .irp    c,,eq,ne,cs,cc,mi,pl,vs,vc,hi,ls,ge,lt,gt,le,hs,lo
        .macro  ret\c, reg
+
+       /* ARMv4- don't know bx lr but the assembler fails to see that */
+#ifdef __ARM_ARCH_4__
+       mov\c   pc, \reg
+#else
        .ifeqs  "\reg", "lr"
        bx\c    \reg
        .else
        mov\c   pc, \reg
        .endif
+#endif
        .endm
        .endr
 

diff --git a/arch/arm/lib/lib1funcs.S b/arch/arm/lib/lib1funcs.S
index 700eee5fbbe0c4c8db2d533ffe15a7cb7748f83b..7ff4446dd64449ae7e389832619235704f800e33 100644 (file)
--- a/arch/arm/lib/lib1funcs.S
+++ b/arch/arm/lib/lib1funcs.S
@@ -377,7 +377,7 @@ ENTRY(__gnu_thumb1_case_sqi)
        lsls    r1, r1, #1
        add     lr, lr, r1
        pop     {r1}
-       bx      lr
+       ret     lr
 ENDPROC(__gnu_thumb1_case_sqi)
 .popsection
 
@@ -391,7 +391,7 @@ ENTRY(__gnu_thumb1_case_uqi)
        lsls    r1, r1, #1
        add     lr, lr, r1
        pop     {r1}
-       bx      lr
+       ret     lr
 ENDPROC(__gnu_thumb1_case_uqi)
 .popsection
 
@@ -406,7 +406,7 @@ ENTRY(__gnu_thumb1_case_shi)
        lsls    r1, r1, #1
        add     lr, lr, r1
        pop     {r0, r1}
-       bx      lr
+       ret     lr
 ENDPROC(__gnu_thumb1_case_shi)
 .popsection
 
@@ -421,7 +421,7 @@ ENTRY(__gnu_thumb1_case_uhi)
        lsls    r1, r1, #1
        add     lr, lr, r1
        pop     {r0, r1}
-       bx      lr
+       ret     lr
 ENDPROC(__gnu_thumb1_case_uhi)
 .popsection
 #endif

diff --git a/arch/arm/lib/memcpy.S b/arch/arm/lib/memcpy.S
index eee7a219ce3609190df322418749a3d77f47f5f6..a1c996f94ef283fd1be5758340f16ada6a47f14d 100644 (file)
--- a/arch/arm/lib/memcpy.S
+++ b/arch/arm/lib/memcpy.S
@@ -59,7 +59,7 @@
 #endif
 ENTRY(memcpy)
                cmp     r0, r1
-               bxeq    lr
+               reteq   lr
 
                enter   r4, lr
 
@@ -148,7 +148,7 @@ ENTRY(memcpy)
                str1b   r0, ip, cs, abort=21f
 
                exit    r4, lr
-               bx      lr
+               ret     lr
 
 9:             rsb     ip, ip, #4
                cmp     ip, #2
@@ -258,7 +258,7 @@ ENTRY(memcpy)
 
        .macro  copy_abort_end
        ldmfd   sp!, {r4, lr}
-       bx      lr
+       ret     lr
        .endm
 
 ENDPROC(memcpy)

diff --git a/arch/arm/lib/relocate.S b/arch/arm/lib/relocate.S
index 5102bfabde4acd4351173364e9111ea74efcc1e4..dd6f2e3bd5e0ecee25332d635a2744d971070fb3 100644 (file)
--- a/arch/arm/lib/relocate.S
+++ b/arch/arm/lib/relocate.S
@@ -61,7 +61,7 @@ ENTRY(relocate_vectors)
        stmia   r1!, {r2-r8,r10}
 #endif
 #endif
-       bx      lr
+       ret     lr
 
 ENDPROC(relocate_vectors)
 
@@ -127,13 +127,7 @@ relocate_done:
        mcr     p15, 0, r0, c7, c10, 4  /* drain write buffer */
 #endif
 
-       /* ARMv4- don't know bx lr but the assembler fails to see that */
-
-#ifdef __ARM_ARCH_4__
-       mov     pc, lr
-#else
-       bx      lr
-#endif
+       ret     lr
 
 ENDPROC(relocate_code)
 

diff --git a/arch/arm/lib/setjmp.S b/arch/arm/lib/setjmp.S
index 176a1d5315bfb597d97b7583596fc9cb478619d3..2f041aeef01c819e546f12d0b5a5fa8ffb64c8be 100644 (file)
--- a/arch/arm/lib/setjmp.S
+++ b/arch/arm/lib/setjmp.S
@@ -17,7 +17,7 @@ ENTRY(setjmp)
        mov  ip, sp
        stm  a1, {v1-v8, ip, lr}
        mov  a1, #0
-       bx   lr
+       ret  lr
 ENDPROC(setjmp)
 .popsection
 
@@ -31,6 +31,6 @@ ENTRY(longjmp)
        bne  1f
        mov  a1, #1
 1:
-       bx   lr
+       ret  lr
 ENDPROC(longjmp)
 .popsection